An archway is a passage or entrance that you walk through under an arch, or under a row of arches. Think of the curved opening in an old wall, a temple gate, or a school corridor where the ceiling is a curve: the space you actually pass through is the archway. It is an ordinary building word, not fancy. Though actually, English also uses arch for the curved structure itself; the archway is the way — the path — under it. In London there is a place called Archway, named after a high arched bridge, but that is a place name sitting on top of this meaning, not a second meaning you need for the word in general.